[BUG] Claude Code 2.1.243 immediately segfaults on Arch Linux x86_64

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code

### What's Wrong?

Claude Code 2.1.243 immediately crashes with a segmentation fault on Arch Linux x86_64.

The crash occurs before Claude Code starts and even happens when running `claude --version`, so it does not appear to be related to a project, configuration, MCP server, or Claude model.

Claude Code 2.1.241 works correctly on the exact same system and installation, making this appear to be a regression in 2.1.243.

### What Should Happen?

`claude --version` should print the installed Claude Code version, and `claude` should start normally.

Version 2.1.241 behaves correctly on the same machine.

### Error Messages/Logs

```shell
$ claude --version
Segmentation fault (core dumped)

The kernel reports:
claude[5903]: segfault at 0 ip 0000000001d10458 sp 00007ffc46cae2c0 error 4 in 2.1.243[1b0f458,1953000+3b33000] likely on CPU 5 (core 5, socket 0)

Code: cc cc 55 48 89 e5 48 89 fe 48 8b 05 82 19 78 03 48 89 f9 48 c1 e9 1d 48 8b 84 c8 80 00 00 00 89 f1 c1 e9 0d 81 e1 f8 ff 00 00 <48> 8b 3c 08 48 85 ff 74 1e 48 8b 07 64 48 33 04 25 00 00 00 00 75

A second invocation produced the same crash at the same instruction address:
claude[14070]: segfault at 0 ip 0000000001d10458 sp 00007ffd86b15ce0 error 4 in 2.1.243[1b0f458,1953000+3b33000] likely on CPU 9 (core 1, socket 0)
```

### Steps to Reproduce

Use an **Arch Linux x86_64** system.

Install **Claude Code** using the official native installer.

Update **Claude Code** to version **2.1.243**.

Run:
```bash
claude --version
```

Observe:
```text
Segmentation fault (core dumped)
```

Verify the installed binary:
```bash
readlink -f ~/.local/bin/claude
```

Output:
```text
/home/ripple/.local/share/claude/versions/2.1.243
```

Run the previous installed version directly:
```bash
~/.local/share/claude/versions/2.1.241 --version
```

Version **2.1.241** successfully outputs:
```text
2.1.241 (Claude Code)
```

Pointing the `claude` symlink back to **2.1.241** restores functionality:
```bash
ln -sf ~/.local/share/claude/versions/2.1.241 ~/.local/bin/claude
```

Then:
```bash
\$ claude --version
2.1.241 (Claude Code)
```

### Claude Model

None

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

2.1.241

### Claude Code Version

2.1.243 (Claude Code)

### Platform

Other

### Operating System

Other Linux

### Terminal/Shell

Other

### Additional Information

**Claude Code** is installed using the official native installer.

The installation maintains multiple versions under:
```text
~/.local/share/claude/versions/
```

The installed versions at the time of testing were:
* `2.1.238`
* `2.1.240`
* `2.1.241`
* `2.1.243`

The `claude` executable is a symbolic link:
```text
~/.local/bin/claude -> ~/.local/share/claude/versions/2.1.243
```

The issue can be reproduced without opening a project or loading any **Claude Code** configuration.

The crash occurs immediately when executing the **2.1.243** binary:
```bash
~/.local/share/claude/versions/2.1.243 --version
```

While the previous version works:
```bash
~/.local/share/claude/versions/2.1.241 --version
```

Result:
* **2.1.243** -> `Segmentation fault`
* **2.1.241** -> Works normally

The kernel reports the segmentation fault occurring inside the **2.1.243** executable itself.

The crash has occurred on different CPU cores across separate invocations:
* Likely on **CPU 5** (core 5, socket 0)
* Likely on **CPU 9** (core 1, socket 0)

This makes the issue highly reproducible and appears to indicate a problem specific to the **2.1.243** binary/runtime on this environment rather than a project-specific configuration issue.

Start with the `claude --version` entry point and reproduce the crash using the 2.1.243 binary on Arch Linux x86_64, then compare it with 2.1.241 using the commands and core-dump details provided. Done means the current binary no longer segfaults before startup, `claude --version` prints its version, and `claude` starts normally.

索引モデルが issue の本文から書いたものです。